摘要 |
FIELD: photography.SUBSTANCE: lens with variable focal distance for cooled detectors, having movable and fixed components, is characterized by five components, located in-series on the beam path, and includes six lenses, wherein each head component is a fixed single positive lens, second component is negative and movable, third component is positive and moving, second and third components are made so that the second surface of the second component, which is concave, and the first surface of the third component, which is convex, face in opposite directions, the value of the movement of the second component does not exceed 0.1 f′ max, and the distance between the third and fourth components does not exceed (0.13÷0.16) f′ max, wherein the aperture diaphragm is located behind the fifth component at a distance of 0.55 f′ min from the last lens surface.EFFECT: technical result - reduced weight and shorter length due to reduced number of lenses, easier production owing to fewer aspheres and higher image quality in the entire range of variation of focal distances.1 cl, 8 dwg |